Nikita Tawanda Tavengwa

Sequestration of U(VI) from aqueous solutions using precipitate ion imprinted polymers endowed with oleic acid functionalized magnetite

AbstractnThe use of a polymeric sorbent material embedded with oleic acid coated magnetic particles as selective sorbents for the removal of U(VI) ions from industrial waste effluents was studied. In the presence of other competing ions [Th(IV) and Ni(II)], U(VI) was preferentially adsorbed. Inclusion of nano-magnetic particles in the polymer matrix aided the separation of the sorbents from aqueous solutions by application of external magnetic field. High recoveries indicated that the sorbent is suitable for application in contaminated water.

Application of magnetic molecularly imprinted polymers for the solid phase extraction of selected nitroaromatic compounds from contaminated aqueous environments

ABSTRACT Magnetic molecularly imprinted polymers (MIPs) were successfully synthesized by bulk polymerization for the extraction of nitroaromatic compounds (NACs). Based on the HPLC method, the linear calibration range of 0.5–5 mg L−1 for 2,4-dinitrotoluene, nitrobenzene and 2-nitrotoluene gave detection limits of 13.6, 7.7 and 27.2 µg L−1, respectively, and good correlation values of R2 > 0.993 of all the analytes were obtained. The optimum sorption was at a sorbent dosage of 5 g L−1, a contact time of 15 min and at pH 8. Recoveries for 2,4-dinitrotoluene, nitrobenzene and 2-nitrotoluene from spiked real water samples were all 82%.

Investigation of As(V) removal from acid mine drainage by iron (hydr) oxide modified zeolite

In this work, the synthesis of iron (hydr) oxide modified zeolite was achieved through precipitation of iron on the zeolite. The structure and surface morphology of iron (hydr) oxide modified zeolite (IHOMZ) was studied by scanning electron microscopy (SEM), coupled with an energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FT-IR) spectra. The efficiency of IHOMZ was then investigated through batch technique for the extraction of As(V) from mine waste water. The optimum parameters for maximum As(V) adsorption were: an initial As(V) concentration (10xa0mgxa0L-1), adsorbent dosage (3.0xa0g), contact time (90xa0min) and temperature (53xa0°C). The initial pH of the solution had no compelling effect on As(V) adsorption by IHOMZ. However, adsorption capacity was significantly affected by the solution temperature with 53xa0°C registering the maximum removal efficiency. The thermodynamic parameters: Entropy (ΔS°xa0=xa00.00815xa0kJ (K mol)-1), variation of the Gibbs free energy (ΔG°) and enthalpy (ΔH°xa0=xa09.392xa0kJxa0mol-1) of As(V) adsorption onto IHOMZ system signified a non-spontaneous and endothermic process. It was noted that Freundlich isotherm model exhibited a better fit to the equilibrium experimental data, implying that the adsorption process occurred on a heterogeneous surface. The kinetic data from As(V) adsorption experiments was depicted by the pseudo-second-order kinetic model (R2xa0>xa00.999), suggesting a chemisorption adsorption process. The experimental batch equilibrium results indicated that IHOMZ could be used as an effective sorbent for As(V) ion extraction from acid mine drainage.